Transformer bushing



Patented Dec. 29, 1953 TRANSFORMER BUSHING Joseph C. Joublanc, Zanesville, Ohio, assignor to McGraw Electric Company, Milwaukee, Wis., a corporation of Delaware Application June 9, 1951, Serial No. 230,733

6 Claims. 1

' My invention relates to a combination terminal connector and a bushing for electrical apparatus such as transformers, etc.

One object is to provide a bushing that is completely coordinated with the transformer insulation and incorporates a bifurcated bolt connector for clamping the end of a lead in a nonslipping, vise-type engagement.

Another object is to provide a transformer bushing that will give greater protection to linemen because of the enclosure of all live parts and including a connector to which line leads can be attached without the aid of tools.

And finally it is an object of this invention to provide a bushing assembly for electrical circuits which will serve as seal against the entrance of moisture into and the egress of oil from an electrical apparatus tank, which will reduce to a minimum resistance in the connection between internal and external leads, and in which the connector operating handle will not be accidentally removed but can easily be removed by intent.

Other objects will appear from time to time in the course of the specification and claims.

An embodiment of my invention is illustrated in the accompanying drawing in which:

Fig. 1 is a sectional view taken on the axis of a bushing as it appears when mounted in a horizontal position relative to the casing shown in fragentary section.

Fig. 2 is a view similar to Fig. 1 illustrating a second version of my improved bushing with a part in section.

Fig. 3 is an enlarged detail illustration partly in section of the bifurcated bolt and associated parts as viewed from the top relative to Fig. 1.

Fig. 4 is a fragmentary View of the knob assembly as viewed from the left relative to Figs. 1 and 2.

Like reference characters indicate similar parts in the various figures of the drawing.

Referring to Fig. 1, I show a fragment of a transformer casing I witha cover 2 and a sealing member 3 between them. Extending perpendicularly through an opening 4 in the side wall of the casing I is a bushing 5. This bushing 5 is preferably made of porcelain and extending therethrough from end to end is a bore 8 having at one end a portion 1 of enlarged diameter providing an annular shoulder upon which an insulating ring a is supported and firmly secured. The enlarged bore portion terminates at one end in an outwardly flared portion 3 which has a pair of radial openings It and I! positioned at 90 from each other.

A bushing flange l2 on the bushing 5 rests on a resilient washer l3 held in air and fluid tight contact with the washer by securing means comprising a coil spring I4 surrounding the bushing and positioned in the annular groove I5 on the periphery of the bushing, a plate 16 surrounding the bushing and engaging the spring 14, and a plurality of bolts I! threaded through the plate It and engaging the inner wall of the casing I.

Secured in the bore of the bushing 5 is a connector 18 comprising an end is having a socket 20 for attaching the transformer terminal, an enlarged portion 2! having an annular groove 21a and diametrically opposed flattened faces 22, and threaded bifurcated portions 23 having the threads removed at 24.

As shown in Fig. 1, the enlarged portion 21 of the connector is positioned in the bore of the insulating ring 8. A resilient retaining ring 25 positioned in the annular groove Zia engages a resilient sealing ring 28, and nut 2! threaded on the connector clamps a locking ring 28 to the insulating ring 8 with tabs 29 on the ring 28 engaging the faces 22. Integral with and extending outwardly from the locking ring 28 and through the opening H is an electrode 44.

Positioned between the bifurcations of the connector and slidable longitudinally thereof is a clamping jaws 30 having a serrated pressure surface 3|. Threaded on the bifurcations is a sleeve 32 which is rotatable relative to the clamping jaw but held in engagement therewith by means of tabs 33 engaging one side of the sleeve portion 32 and tabs 34 engaging the inner side 35 of the sleeve portion 32.

A handle or knob 38 is secured to the end 31 of the sleeve 32 by means of cement 38 in the socket 39 of the handle.

In Fig. 2 I show in elevation with a part broken away, a similar bushing except that it has only one wire entrance opening 43 positioned radially from the inner bore. This opening .9 is sufll ciently large to accommodate several wires. In this view the connector 18 is turned from its position shown in Fig. 1 so that the space between the legs of the threaded bifurcated portion 23 is in line with the wire entrance 40 of the bushing 5. A spill-gap electrode 4! also extends through this entrance from the acting space of the clamping jaw 39 to the outside of the bushing.

Fig. 3 is an enlarged view of the connector [8 turned 90 from the position shown in Fig. 1 and illustrates hou the tabs 29 of the locking ring 28 engages the faces 22 in conjunction with the nut 27. This view also illustrates the sleeve 32 in threaded association with the bifurcated portions 23 and in rotatable relation to the slidable clamping jaw 30.

Another view of the sleeve 32 and clamping jaw attached to the knob 36 can be seen in Fig. 4. The end 31 of the sleeve 32 is fastened into the socket 39 of the knob 36 by some desirable cementitious material 38. The openings d2 on each side of the clamping jaw 30 and within the sleeve 32 are adapted to receive the threaded bifurcated legs 23 when mounted as shown in Fig. 1. V

The use and operation of my invention are as follows: v

It is the constant aim of everyone in the electrical field to safeguard the lives of the linemen; With this in mind I devised an improved bushing for transformers which can be used on either the primary or secondary line by varying the size. The advantages of this bushing are an improvement in appearance, a reduction in overall size, and a means of attaching the cables to the bushing whereby the lines are completely enclosed in the bushing. The linemen can connect the cables without contacting the dangerous live wires and without the use of tools. Any size cable can be attached because I use a vise-typejaw 3! to hold the cables in the connector It. The connector I8 is designed as a bifurcated bolt which reduces contact resistance between internal lead and line lead.

To attach aline to the bushing 55 the lineman inserts the cable into the entrance in near the knob. This opening is in line with the slot between the bifurcated portions 23 of the connector 18. It is easily visible to the lineman as to where to thread the cable.

A pressure shoe 33 with a grooved surface 3| is carried by .a sleeve 32 and knob 36 assembly on the threads of the bifurcated portion '23 of the connector i8. This pressure shoe 3% forms a jaw with the seat between the legs of the bifurcated portions 23 so that when the knob 36 is turned and the threaded section of the sleeve 32 travels on the threaded section of the bifurcated bolt the grooved surface 3| of the pressure shoe 30 clamps the cables firmly in jaw-like manner. Thus, it can be seen that the jaw can be adjusted by means of the knob to fit various sized cables and that its grooved surface prevents slipping.

The bifurcated portion of the connector l8 has a section 24 where the threads have been removed. This is to prevent accidental removal of the knob. When the lineman is turning the knob 36 to move the jaw 33 to release position and the threaded portion of the sleeve 32 reaches the place where the threads are disengaged from the threads on the bifurcations and positioned in the unthreaded sections 24, he knows that the jaw 30 is out of obstructing relation to the opening ID.

If for some reason, he should wish to remove the.

knob .35 and clamping jaw 33 from the bushing 5 he will engage the threaded sleeve 32 with threads 43' at the outer end of the unthreaded section 24 and with a few turns on these threads 43, the knob 35 can be removed.

From the foregoing, it will be apparent that I have provided a novel combination terminal bushing and connector which affords easy manipulation of the connector with a minimum risk that the operator will contact live parts. Further, the construction is relatively simple, is easily assembled, can be quickly repaired, and is suitable for use with standard apparatus casings without requiring alterations thereof.

I claim:

'1. The combination with a lead-in bushing for an electrical apparatus casing, the bore of said bushing having intermediate its ends an inwardly and bifurcated end being embraced by said shoulder, a nut threaded on said bifurcated end and engaging said shoulder within said outer chamher, said means and nut clampingly engaging said shoulder and anchoring said bolt against longitudinal movement within said bushing, the bifurcations of said bolt being disposed on opposite sides of a plane substantially coincident with the axes of said bore and aperture, and clamping means, said clamping means comprising a jaw slidable between said bifurcations, an actuator threaded on said bifurcations and rotatably so cured to said jaw, and an insulating handle on said actuator overlying said outer chamber and serving as a closer therefor.

2. The combination with a lead-in bushing for an electrical apparatus casing, the bore of said bushing having intermediate its ends an inwardly extending annular shoulder dividing said bore into inner and outer chambers and further hav ing a radial aperture opening into said outer chamber between said shoulder and one of said ends, of a connector bolt in the bore of said bushing having a socketed shank portion disposedin said chamber and projecting toward the other of said ends, means secured on and projecting laterally from said shank and engaging said shoulder within said inner chamber, said bolt having a bifurcated end in said outer chamber and being provided with spaced threaded portions substantially co-extensive with said bifur= cated end, said spaced threaded portions defining an unthreaded annular section therebetween, said bolt having a portion intermediate said shank portion and said bifurcated end embraced by said shoulder, a nut threaded on said bifurcated end and engaging said shoulder within said outer chamber, said means and nut clampingly engaging said shoulder and anchoring said bolt against longitudinal movement within said bushing, the bifurcations of said bolt being disposed on both sides of a plane substantially coincident with the axes of said bore and aperture, and clamping means, said clamping means comprising a jaw slidable between said bifurcations, and an actuator threaded on said bifurcations and rotatably secured to said jaw, said actuator being disengageable with said threaded portions at said unthreaded annular section, and an insulating han dle on said actuator overlying said outer chamber and serving as a closer therefor.

3. The combination with a lead-in bushing for an electrical apparatus casing, the bore of said bushing having intermediate its ends an inwardly extending annularshoulder dividing said bore into inner and outer chambers and further hav ing a radial aperture opening into said outer chamber between said shoulder and one of said ends, of a connector bolt'in the bore of said bush ing having a socketed shank portion disposed in said chamber and projecting toward the other of said ends, means secured on and projecting laterally from said shank and engaging said shoulder within said inner chamber, said bolt having a bifurcated end in said outer chamber and a portion intermediate said shank portion and bifurcated end being embraced by said shoulder, a nut threaded on said bifurcated end and engaging said shoulder within said outer charnber, said means and nut clampingly engaging said shoulder and anci iorin said bolt against longitudinal movement within said bushing, the bifurcations of said bolt being disposed on opossite sides of a plane substantially coincident th the axes of said bore and aperture, rota onal re straining nieans interacting between sa' and said bushing for preventing relative Z'Qtdu-0fl therebetween, and clamping means, comprising a jaw slidable between sa tions, an actuator threaded on said huurc tiohs and rotatably secured to said jaw, and an insulating handle on actuator o rlying id outer chamber serving as a closer therefor.

The combination with a lead-in bushing for an electrical apparatus casing, the bore of said bushing having intermediate its e ds an inwardly extending annular shoulder dividing said bore into inner and outer chambers and further hav-- ing a radial aperture opening into said outer chamber between said shoulder and one of said ends, of a connector bolt in the bore of bush ing having a socketed shank portion in said chamber and projecting toward the other of said ends, means secured on and projecting laterally from said shank and engaging said shoulder within said inner chamber, said bolt having a bifurcated end in said outer chamber and being provided with spaced threaded portions substantially eta-extensive with said bifurcated end, said spaced threaded portions defining an unthreaded annular section therebetween, said bolt having a portion intermediate said shank portion and said bifurcated end embraced by said shoulder, a nut threaded on said bifurcated end and engaging said shoulder within said outer chamber, said means and nut clampmgly engaging said shoulder and anchoring said bolt against lateral movement within said bushing, rotatlonal restraining means interacting between said bolt and said bushing for preventing relative rotation therebetween, the bifurcations of said bolt being disposed on both sides of a plane substantially coincident with the axes of said bore and aperture, and clamping means, said clamping means comprising a aw shdable between said birurcations, and an actuator threaded on sand blfLlI'Caw tions and rotatabry secured to said jaw, said actu ator being oisengageable with said threaded portions at said untnreaded annular section, and an insulating handle on said actuator overlying said outer chamber and servmg as a closer therefor.

5. The combination with a lead-in bushing for an electrical apparatus casing, the bore of semi bushing having intermediate its ends an inward- 1y extending annular shoulder dividing said bore into inner and outer chambers and Iurther having a radial aperture opening into said outer chamber between said shoulder and one of said ends, of a connector bolt in the bore of said bushlng having a soolzeted shank portion disposed in said chamber and projecting toward the other or said ends, a stop nxedly mounted on and projecting laterally from said shank and engaging said shoulder within said inner chamher, said bolt having a threaded bifurcated end. in said outer chamber and further having a portion providing opposed fiat sides, rotational restraining means on said bolt and slidably engageable with said opposed sides and interacting between said bolt and said bushing to prevent relative rotation therebetween, said bolt having portion intermediate said shank portion and said opposed fiat sides embraced by said shoulder, a nut threaded on said bifurcated end and engaging and holding 1 training means clamped to said shoulder me in said outer chamber, said stop and nut clainpingly engaging said should 1' and anchoring said bolt against lateral movement with said bushing, the bifucations of b it being disposed on opposits of a plane substantially coincident with the axes of said bore and aperture, a clamping means, said clamping means oomprl-=- ing a jaw slidable between said bifurcations, an actuator threaded on said bifurcations ro tatably secured to said jaw, and an insulating handle on said actuator overly g s chamber and serving as a closer therefor.

8. The combination with a lead-in bushing f0 an electrical apparatus casing, the bore of sad bushing having intermediate its ends an inwardly extending annular shoulder .ividin bore into inner and outer chambers u having a radial aperture opening int 5 chamber between said shoul er and one ends, of a connector bolt in bore or bushing having a socketed shank portion posed in said inner chamber and projec" toward the other of said ends, a stop mounted on and projecting laterally from shank and engaging said shoulder within inner chamber, said bolt having a threaded iurcated end in said outer chamber and further having diametrically opposed fiat substantially (ac-extensive with said end, rotational restraining means on said bolt slidably en gageable with said opposed sides and interacting between said bolt and said bushing to nrev it relative rotation therebetween, said bolt haw/iia portion intermediate said shank portion and opposed fiat sides embraced by said shoulder, a nut threaded on said bifurcated end and en gaging and holding said restraining means clamped to said shoulder within said outer chamber, said stop and nut clampingly enga ing said shoulder and anchoring said bolt against lateral movement with said bushing, the bi-- furcations of said bolt being disposed on o;;- posite sides of a plane substantially coincident with the axes of said bore and apert re, clamping means, said clamping means ing a jaw slidable between said bifurcations, an actuator threaded on said bifurcations and rotatably secured to said jaw, and an insulatin handle on said actuator overlying said chamber and serving as a closer therefor.

JOSEPH C. JOUBLANC.

nezlerences Cited in the file of this UNITED STATES PATENTS 

